Apparatus and method of forming an applied film

ABSTRACT

There is provided an apparatus including: a processing cup having an opening opened upward to allow a substrate to be loaded and unloaded, an exhaust port for exhausting an unnecessary atmosphere produced in forming a film applied on the substrate, and an aspiration port for aspirating external air; and an aspiration device aspirating the unnecessary atmosphere through the exhaust port, wherein when the substrate is accommodated in the opening of the processing cup, the substrate has a perimeter spaced from the opening by a predetermined gap, and below the substrate accommodated in the processing cup there is formed an exhaust flow path extending from the aspiration port to the exhaust port.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of pending U.S. applicationSer. No. 11/501,740 filed Aug. 10, 2006, which is herein incorporated byreference. Further, parent application Ser. No. 11/501,740 claimspriority to Japanese Patent Application No. 2005-249299, filed Aug. 30,2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to apparatuses and methods offorming a film of liquid applied on a substrate and particularly toapparatuses dropping a liquid to be applied on an upper surface of asubstrate held substantially horizontally and rotated as controlled todisperse the liquid in the form of a film to form a film to be appliedand methods of forming such film.

2. Description of the Background Art

In fabricating a semiconductor device a photolithography process isperformed including, e.g., the step of applying resist liquid serving asa liquid to be applied on a semiconductor wafer (hereinafter simplyreferred to as a “wafer”) serving as a substrate to be processed to forma film of the resist, the step of exposing the film of the resist toform the film of the resist in a predetermined pattern, the step ofheating the exposed film of the resist to promote a chemical reactiontherein (i.e., the step of post-exposure baking), the step of developingthe exposed film of the resist, and the like in order to form apredetermined pattern of the resist on the wafer.

Of the series of process steps, the step of applying the resist isperformed for example in a well-known apparatus employing spin-coatingto form an applied film, as indicated in Japanese Patent Laying-Open No.07-320999. FIG. 7 shows in configuration the apparatus indicated in thedocument such that it is partially simplified. FIG. 7 shows an apparatus200 forming an applied film. More specifically, a spin chuck 201 with awafer W placed and thus fixed thereon is rotated and a solvent (thinneror the like) serving as a solvent for resist liquid is initially droppedat a center of an upper surface of wafer W from a solvent feedingmechanism 202 through a nozzle 203 and thus dispersed, and the resistliquid is then dropped by a resist feeding mechanism 204 through anozzle 205. The dropped resist liquid is dispersed from the center ofthe wafer toward the perimeter of the wafer spirally by the rotationalforce of wafer W and the centrifugal force and thus applied on thewafer.

When spin-coating is employed to perform an application process, asindicated in the document, the resist liquid dispersed on wafer W thatis excessive is spun away from wafer W by the force of rotation of waferW. Of the resist liquid spun and thus scattered away, a portion isaccommodated in an application cup 206 and a portion forms an atmospherein the form of a mist around wafer W. Accordingly the configurationindicated in the document has an exhaust port 207 under application cup206 to aspirate therethrough the mist formed around wafer W.

The configuration with application cup 206 having an upper portion openand exhaust port 207 located under wafer W, as shown in FIG. 7, however,forms an exhaust flow path which affects the film to be uneven inthickness, and this is a technological issue to be addressed.

More specifically, when the mist formed around wafer W is aspiratedthrough exhaust port 207, as shown in the figure, the mist is aspiratedtogether with external air present above wafer W. This forms a downwardexhaust flow path. As a result, wafer W receives larger wind pressure atthe perimeter than at the center. The perimeter is thus dried faster andon the dried resist the resist liquid is further applied resulting inwafer W having a film thereon larger in thickness at the perimeter thanat the center.

Furthermore, as shown in FIG. 7, between application cup 206 and wafer Wa large gap G is formed. As such, the mist also leaks and thus moves toabove wafer W. Accordingly, aspirating through exhaust port 207 all ofthe mist having moved to above wafer W requires powerful aspiration,which is also an issue to be addressed.

Furthermore, measuring an amount of exhaust in the configuration of FIG.7 requires that an anemometer, a flowmeter and/or the like be arrangedin the exhaust flow path downstream, i.e., at exhaust port 207 or thelike. In that case, however, the measuring instrument is contaminated bythe mist and cannot measure the amount of exhaust precisely.

SUMMARY OF THE INVENTION

The present invention contemplates an apparatus that drops a liquid tobe applied on an upper surface of a substrate substantially horizontallyheld and rotated as controlled and by the force caused by the rotatedsubstrate disperses the liquid in the form of a film to form an appliedfilm, that can form the film uniformly in thickness and can also reducethe liquid in the form of mist scattering around the substrate informing the film that leaks to above the substrate, and also reduceaspiration required to exhaust the liquid in the form of the mist, andalso measure an amount of exhaust with precision, and a method offorming such applied film.

The present invention provides an apparatus that drops on a substrate aliquid to be applied thereon and rotates the substrate to cause a forceto disperse the liquid in a form of a film to form a film applied on anupper surface of the substrate, including: a substrate holding androtating device substantially horizontally holding and thus rotating thesubstrate; a device feeding the liquid to be applied, dropping theliquid to be applied onto the upper surface of the substrate; aprocessing cup having an opening opened upward to allow the substrate tobe loaded and unloaded, an exhaust port for exhausting an unnecessaryatmosphere produced in forming the film applied on the substrate, and anaspiration port for aspirating external air; and an aspiration deviceaspirating the unnecessary atmosphere through the exhaust port, whereinwhen the substrate is accommodated in the opening of the processing cup,the substrate has a perimeter spaced from the opening by a predeterminedgap and substantially separates a processing space located above thesubstrate and a space located below the substrate, and below thesubstrate accommodated in the processing cup there is formed an exhaustflow path extending from the aspiration port to the exhaust port, withthe gap and the exhaust flow path communicating with each other.

In the present apparatus preferably the perimeter of the substrate andthe opening are spaced by a gap of at most 3 mm in a radial direction ofthe substrate and a gap within a range of 0.5 mm to 2 mm in a directionof a height of the substrate and the perimeter of the substrate is lowerin level than the opening of the processing cup.

The processing cup and the substrate having the opening and theperimeter, respectively, with a predetermined space interposedtherebetween as described above can separate a processing space locatedabove the substrate for applying a liquid thereon, and a space locatedbelow the substrate for exhaust and effluent. This can reduce or preventan unnecessary atmosphere containing the applied liquid that forms amist in the processing cup and thus leaks above the substrate.

Furthermore the processing cup that is provided with the aspiration portfor aspirating external air and the exhaust port for exhausting airoutside the processing cup can have an exhaust flow path formed therein.Even with small aspiration, the mist formed in the process forming anapplied film can be exhausted.

Furthermore in the above described configuration there is not externalair intensely flowing in from the opening of the processing cup as airis exhausted, and the substrate can have a perimeter with the resistless dried. A film of the resist that is excellently uniform inthickness can thus be obtained.

In the present apparatus preferably the aspiration port is provided witha sensor measuring aspirated air in flow rate.

Furthermore the sensor sensing the amount of air aspirated that isprovided at the aspiration port located upstream in the exhaust flowpath can be protected from contamination by the mist and thus measurethe aspirated air in flow rate with precision. Furthermore, as the gapformed between the opening of the processing cup and the perimeter ofthe substrate introduces atmosphere in a small amount, the air aspiratedand the air exhausted are substantially equal in flow rate. Furthermore,no contamination contributes to reduced cost for maintenance.

In the present apparatus preferably in the exhaust flow path downstreamof the sensor a backflow preventing portion is provided to prevent theunnecessary atmosphere from flowing backward into the aspiration port.

Thus if an aspiration device aspirating a mist acting as an unnecessaryatmosphere is not driven and thus stops, the backflow preventing portioncan reduce or prevent the mist flowing back into the aspiration port andcontaminating the sensor.

Preferably the present apparatus further includes a lid engaged with anupper portion of the processing cup for forming the processing spacelocated above the substrate and substantially sealed.

Preferably the present apparatus further includes an atmosphere controldevice feeding the processing space with a solvent for the liquid in aform of a mist, wherein while the atmosphere control device feeds theprocessing space with the solvent in the mist, the liquid to be applieddropped by the device feeding the liquid to be applied is dispersed asthe substrate holding and rotating device rotates the substrate.

This can suppress evaporation of the solvent dispersed in forming anapplied film and thus prevent the substrate from having a perimeter withthe dispersed applied liquid dried and thus solidified thereon.

Thus the applied liquid can form a film uniform in thickness, and theliquid can also be reduced in amount for use and exhaust and effluentcan also be reduced in amount.

The present invention provides a method of forming an applied film,dropping on a substrate a liquid to be applied thereon, and rotating thesubstrate to cause a force to disperse the liquid in a form of a film toform a film applied on an upper surface of the substrate, including thestep of: substantially horizontally holding the substrate on a substrateholding and rotating device; dropping the liquid on an upper surface ofthe substrate rotating on the substrate holding and rotating device; andexhausting an unnecessary atmosphere produced in forming the filmapplied on the substrate, wherein the step of exhausting is performedsuch that a processing space located above the substrate and a spacelocated below the substrate are substantially separated.

A processing space located above the substrate for applying a liquidthereon, and a space located below the substrate for exhaust andeffluent can be separated. This can reduce or prevent an unnecessaryatmosphere leaking above the substrate.

In the present method preferably the step of dropping is performed suchthat the processing space located above the substrate is substantiallysealed.

In the present method preferably the step of dropping includes the stepof feeding the processing space with a solvent for the liquid in a formor a mist and with the solvent fed in the mist the liquid is dispersedas the substrate is rotated.

This can suppress evaporation of the solvent dispersed in forming anapplied film and thus prevent the substrate from having a perimeter withthe dispersed applied liquid dried and thus solidified thereon.

Thus the applied liquid can form a film uniform in thickness, and theliquid can also be reduced in amount for use and exhaust and effluentcan also be reduced in amount.

The present invention can thus provide an apparatus that drops a liquidto be applied on an upper surface of a substrate substantiallyhorizontally held and rotated as controlled and by the force caused bythe rotated substrate disperses the liquid in the form of a film to forman applied film, that can form the film uniformly in thickness and canalso reduce the liquid in the form of mist scattering around thesubstrate in forming the film that leaks to above the substrate, andalso reduce aspiration required to exhaust the liquid in the form of themist, and also measure an amount of exhaust with precision, and a methodof forming such applied film.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view schematically showing a configuration of a resistapplication and development system equipped with a resist applicationprocess unit serving as the present apparatus forming an applied film.

FIGS. 2 and 3 are front and rear views, respectively, of the resistapplication and development system shown in FIG. 1.

FIGS. 4 and 5 are cross sections schematically showing configurations ofa resist application process unit serving as the present apparatus infirst and second embodiments, respectively.

FIG. 6 is a partially enlarged view of another embodiment around anaspiration port.

FIG. 7 is a cross section schematically showing a configuration of anapparatus forming an applied film, as conventional.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter the present apparatus forming an applied film will bedescribed with reference to an embodiment shown in the figures.

As shown in FIG. 1 a resist application and development system 1 isconfigured such that a cassette station 2 loading and unloading 25wafers Ws, for example, externally into and from resist application anddevelopment system 1 in cassettes and loading and unloading wafer W intoand from a cassette C, a processing station 3 having a plurality ofprocessing units arranged in multiple stages to perform a predeterminedprocess in a photolithography process in a single wafer processing, andan interface portion 4 passing and receiving wafer W to and from anexposure device (not shown) provided adjacent to processing station 3are integrally connected together.

Cassette station 2 is provided with a cassette platform 5 such that aplurality of cassettes Cs can be placed thereon in a direction X (inFIG. 1, the upward/downward direction) in a row. Furthermore, cassettestation 2 is provided with a wafer carriage 7 movable on a carrier path6 in the direction X. Wafer carriage 7 is adapted to be also movable ina direction in which wafer W accommodated in cassette 7 is arranged(i.e., a direction Z, or the direction orthogonal to the direction ofthe sheet of FIG. 1), and is adapted to selectively access wafer W ofeach cassette arranged along the X axis.

Furthermore, wafer carriage 7 is adapted to be rotatable around the Zaxis in a direction θ and also capable of accessing a temperatureadjustment unit 60, a transition unit 61 and the like belonging to athird processing device group G3 associated with processing station 3described later.

Cassette station 2 is adjacent to processing station 3, which includesfor example five processing device groups G1-G5 having a plurality ofprocessing devices arranged in multiple stages.

In processing station 3 at a lower side in FIG. 1, adjacent to cassettestation 2 is arranged a first processing device group G1, followed by asecond processing device group G2. Furthermore, at an upper portion inFIG. 1, adjacent to cassette station 2 is arranged a third processingdevice group G3, followed by a fourth processing device group G4 and afifth processing device group G5 in order.

Furthermore between the third and fourth processing device groups G3 andG4 is provided a first transport device 10 adapted to be capable ofselectively accessing each processing device in the first, third andfourth processing device groups G1, G3 and G4 to transport wafer W.

Furthermore between the fourth and fifth processing device groups G4 andG5 is provided a second transport device 11 adapted to be capable ofselectively accessing each processing device in the second, fourth andfifth processing device groups G2, G4 and G5 to transport wafer W.

Furthermore in the first processing device group G1 liquid processingdevices feeding wafer W with a predetermined liquid to perform aprocess, e.g., as shown FIG. 2, resist application process units (COTs)20, 21, 22 applying a resist liquid on wafer W, bottom coating units(BARCs) 23, 24 forming an anti reflection film preventing a reflectionof light in an exposure process are stacked upward in order in fivestages.

Furthermore in the second processing device group G2 liquid processingdevices, e.g., development process units (DEVs) 30-34 for examplefeeding wafer W with developer to perform a development process arestacked upward in order in five stages.

Furthermore in the first and second processing device groups G1 and G2at their respective bottom most stages chemical chambers (CHMs) 35 and36 are respectively provided to feed a variety of processing liquids toliquid processing devices in processing device groups G1 and G2.

Furthermore, as shown in FIG. 3, in third processing device group G3temperature adjustment unit (TCP) 60, transition unit (TRS) 61 passingand receiving wafer W, high-precision temperature adjustment units(CPLs) 62-64 adjusting wafer W in temperature as temperature iscontrolled with high precision, and thermal processing units (BAKEs)65-68 exposing wafer W to high temperature to heat and thus processwafer W are stacked in order in nine stages.

In the fourth processing device group G4 for example a high-precisiontemperature adjustment unit (CPL) 70, pre-baking units (PABs) 71-74heating and thus processing wafer W having resist applied thereon,post-baking units (POSTs) 75-79 heating and thus processing wafer Whaving undergone the development process are stacked upward in order in10 stages.

Furthermore in the fifth processing device group G5 a plurality ofthermal processing devices thermally processing wafer W, e.g.,high-precision temperature adjustment units (CPLs) 80-83 and a pluralityof post-exposure baking units (PEBs) 84-89 heating and thus processingwafer W having been exposed are stacked upward in order in 10 stages.

Furthermore at a positive side of the first transport device 10 (seeFIG. 1) in direction X a plurality of processing devices, e.g., as shownin FIG. 3, adhesion units (ADs) 90, 91 processing wafer W to behydrophobic and heating units (HPs) 92, 93, heating wafer W are stackedupward in order in four stages.

Furthermore at a positive side of the second transport device 11 (seeFIG. 1) in direction X a perimeter exposure unit (WEE) 94 is arrangedfor example to expose wafer W only at an edge selectively.

Furthermore, interface portion 4 is provided with a wafer carriage 41moving on a carrier path 40 extending in direction X, and a buffercassette 42, as shown in FIG. 1. Wafer carriage 41 is adapted to be alsomovable in direction Z and rotatable in direction θ and capable ofaccessing the exposure device (not shown) adjacent to interface portion4, buffer cassette 42 and the fifth processing device group G5 totransport wafer W.

Resist application and development system 1 thus configured allows aseries of photolithography process steps as will be describedhereinafter.

Initially in cassette station 2 a single wafer W is transported fromcassette C, which accommodates wafer W to be processed, by wafercarriage 7 to the third processing device group G3 and loaded intotransition unit (TRS) 61. Therein wafer W is registered and subsequentlytransported to adhesion units (ADs) 90, 91 and thus processed to behydrophobic. Then the wafer undergoes a predetermined cooling process inhigh-precision temperature adjustment units (CPLs) 62-64 and is thentransported to the first processing device group G1 and loaded intoresist application process units (COTs) 20-22 to have a surfacesubjected to a resist application process. Note that from transitiondevice 61 to resist application devices 20-22 wafer W is transported bythe first transport device 10.

Then wafer W is transported by the first transport device 10 to thefourth processing device group G4 and loaded into pre-baking devices71-74 and thus heated as predetermined, i.e., pre-baked. Wafer Wprebaked is transported to perimeter exposure unit (WEE) 94 and exposedonly at an edge.

Thereafter wafer W is transported to the fifth processing device groupG5 and loaded into high-precision temperature adjustment units (CPLs)80-83 and cooled therein, and then carried in interface portion 4 bywafer carriage 41 into buffer cassette 42 and thus temporarily storedtherein.

Wafer W temporarily held in buffer cassette 42 is ejected by wafercarriage 41 and passed to the exposure device (not shown) and exposedtherein.

Wafer W having been exposed is again transported via interface portion 4to the fifth processing device group G5 and loaded into post-exposurebaking units (PEBs) 84-89 to undergo a post-exposure heating process.

Then wafer W is transported by the second transport device 11 to thesecond processing device group G2 and loaded into development processdevices 30-34 and thus developed therein, and then transported to thefourth processing device group G4 and loaded into post-baking units(POSTs) 75-79 and therein undergoes a post-development heating process.Then wafer W is transported to the third processing device group G3 andloaded into high-precision temperature adjustment units (CPLs) 62-64 andcooled therein, and then returned by wafer carriage 7 to cassette C.

Resist application process units (COTs) 20-22 serving as the presentapparatus forming an applied film, will now be described morespecifically. Note that a plurality of resist application process units(COTs) 20-22 arranged are each similarly configured. Accordinglyhereinafter resist application process unit (COT) 20 will be describedrepresentatively to describe their configuration.

As shown in FIG. 4, resist application process unit (COT) 20 includes aspin chuck 51 holding wafer W substantially horizontally, a rotationmechanism 52 rotating spin chuck 51, an ascending and descendingmechanism 53 causing spin chuck 51 to ascend and descend, and aprocessing cup 55 accommodating spin chuck 51.

Note that spin chuck 51 and rotation mechanism 52 configure a substrateholding and rotating device.

Furthermore spin chuck 51 is adapted such that an aspiration mechanism(not shown) operates to produce a vacuum to chuck wafer W and thus allowthe spin chuck to hold the wafer. Furthermore, from above processing cup55, a filter fan unit (FFU) (not shown) feeds clean air in a downwardflow toward wafer W.

Furthermore, above wafer W, a nozzle 56 dropping thinner or a similarsolvent as a solvent for the resist liquid is provided to be movable bya movement mechanism (not shown) horizontally and vertically, and nozzle56 is fed with the solvent by solvent feeding mechanism 57. As well asnozzle 56, above wafer W, a nozzle 58 is provided to be movable by amovement mechanism (not shown) horizontally and vertically and fed withthe resist liquid by resist feeding mechanism 59. Note that resistfeeding mechanism 59 and nozzle 58 together configure a device feedingan applied liquid.

Processing cup 55 includes an outer peripheral member 43 arranged tosurround an outer side of wafer W, an air stream controlling member 44arranged internal to outer peripheral member 43 under and adjacent towafer W and surrounding spin chuck 51, and an internal cup 45 arrangedinternal to outer peripheral member 43 below air stream controllingmember 44.

Outer peripheral member 43 is defined by a first vertical wall 43 a inthe form of a cylinder, a ceiling portion 43 b provided at an upperportion of the first vertical wall 43 a and extending inward therefrom,and an inner peripheral portion 43 c formed integral with an innerperimeter of ceiling portion 43 b and having an internal wall surfaceinclined outward and downward. Note that inner peripheral portion 43 cdefines an opening 55 b for introducing and ejecting wafer W into andfrom processing cup 55.

Air stream controlling member 44 is formed in an annulus surroundingspin chuck 51 and is defined by a first wall 44 a, a second wall 44 band a third wall 44 c provided to form an exhaust flow path. Note thatthe first wall 44 a has an outer side inclined downward to guide intointernal cup 45 the resist liquid recovered in processing cup 55.Furthermore, the third wall 44 c is provided to form the exhaust flowpath.

Furthermore, internal cup 45 is defined by a second vertical wall 45 aformed in the form of a cylinder inner than the first vertical wall 43 aof outer peripheral member 43 and cooperating with the first verticalwall 43 a to define an external-air aspiration port 55 a, and a bottomportion 45 b provided inside from a lower end of the second verticalwall 45 a. Furthermore, bottom portion 45 b is provided with an exhaustport 55 c for exhausting mist formed in processing cup 55, and aneffluent port 55 d for discharging the resist liquid recovered ininternal cup 45.

Furthermore when wafer W is accommodated in processing cup 55 thusformed, wafer W is arranged with its perimeter spaced from opening 55 bby a predetermined gap. More specifically, as shown in FIG. 4, wafer Wis arranged such that the substrate is spaced by a radial gap of at most3 mm and a vertical gap within a range of 0.5 mm to 2 mm and thesubstrate has its perimeter lower in level than the opening of theprocessing cup.

Thus the liquid to be applied that is spun away and thus scattering inprocessing cup 55 impinges on processing cup 55 at inner peripheralportion 43 c and is thus recovered in processing cup 55.

Furthermore, an unnecessary atmosphere containing the resist liquid thathas formed mist in processing cup 55 is slightly aspirated through thegap formed between opening 55 b and the perimeter of wafer W, and thuswill not leak above wafer W. An atmosphere present above the substrateis also aspirated through the gap, although it is aspirated in asignificantly small amount. As such, the liquid applied on the substrateat the perimeter will not be dried faster than that applied on thesubstrate at the other portions.

Furthermore, downstream of exhaust port 55 c, there is provided anaspiration device 550 (not shown). When the aspiration device is driven,an exhaust flow path is formed under wafer W from aspiration port 55 ato exhaust port 55 c.

Furthermore, as the gap and the exhaust flow path communicate with eachother, the mist formed in processing cup 55 passes through the exhaustflow path together with external air aspirated through aspiration port55 a and is exhausted through exhaust port 55 c.

Furthermore a flowmeter 46 measuring a flow rate is provided internal toaspiration port 55 a as a sensor sensing the amount of air aspirated.More specifically, flowmeter 46 is provided upstream in the exhaust flowpath and adapted to be prevented from contamination by the mist. Notethat, as aforementioned, as the gap draws air in a small amount, the airaspirated and the air exhausted are substantially equal in flow rate.

Thus, as the exhaust flow rate can substantially be measured byflowmeter 46, an exhaust flow rate sensor can be installed upstream of aportion at which the mist is generated, and an error in measurementattributed to a mist adhering on the sensor portion can be prevented,allowing an amount of exhaust to be monitored more precisely. In suchconfiguration when the first transport device 10 shown in FIG. 1transports wafer W to resist application process unit (COT) 20, wafer Wis chucked substantially horizontally on spin chuck 51 moved byascending and descending mechanism 53 upward.

Wafer W chucked on spin chuck 51 is moved by ascending and descendingmechanism 53 into processing cup 55 and thus accommodated therein and apredetermined amount of a solvent is dropped through nozzle 56 on theupper surface of wafer W at the center. Subsequently, spin chuck 51 isrotated by rotation mechanism 52 to disperse on wafer W the solventdropped on wafer W.

While the solvent is being dispersed, the resist liquid is droppedthrough nozzle 58 and dispersed, with a film of the solvent interposed,to form a film of the resist on wafer W.

Note that at that time, the resist liquid that is scattered from wafer Wtherearound and thus excessive is recovered by processing cup 55 andpartially forms a mist in processing cup 55.

In processing cup 55, as aspiration device 550 is driven, the exhaustflow path extending from aspiration port 55 a to exhaust port 55 c isformed. The mist formed in processing cup 55 passes through the exhaustflow path as an unnecessary atmosphere together with external airaspirated through aspiration port 55 a and is thus exhausted throughexhaust port 55 c.

Thus the present invention in the first embodiment allows opening 55 band the perimeter of wafer W to have only a small distance therebetweenand separates a processing space located above wafer W in which resistis applied on wafer W and a space located below wafer W for exhaust andeffluent. Thus the applied liquid that is spun away from the perimeterof the substrate can be recovered in the processing cup and the mistformed in processing cup 55 that leaks above wafer W can be reduced orprevented.

Furthermore, aspiration port 55 a for aspirating external air intoprocessing cup 55, and exhaust port 55 c for exhausting outsideprocessing cup 55 are provided. An exhaust flow path can thus be formedin processing cup 55, and a mist produced in forming the film to beapplied can be exhausted even with small aspiration.

Furthermore, as an exhaust flow path is formed, as described above,there is not external air intensely flowing in from opening 55 as air isexhausted, and wafer W at the perimeter can have resist less dried. Afilm of the resist that is extremely uniform in thickness can thus beobtained.

Furthermore, flowmeter 46 that is arranged in aspiration port 55 alocated upstream in the exhaust flow path can be protected fromcontamination by the mist and thus measure an amount of exhaust withhigh precision. Furthermore, no contamination contributes to reducedcost for maintenance.

A second embodiment of the resist application process unit correspondingto the apparatus forming an applied film in accordance with the presentinvention, will be described hereinafter. Note that in FIG. 5 theportion identical in configuration to the first embodiment of the resistapplication process unit (COT) described with reference to FIG. 4 isidentically denoted and its specific description will not be repeated.

Resist application process unit (COT) 20 shown in FIG. 5 differs fromthe configuration of the first embodiment shown in FIG. 4 in that theapplication process is performed in a processing space having a sealedstructure. More specifically, in the configuration of FIG. 5, inaddition to the configuration of spin chuck 51 and processing cup 55shown in FIG. 4, a lid 50 is provided to prevent processing cup 55 fromhaving an upper portion open, and they configure a main portion.

Lid 50 is formed in a dome having an upper center provided with an axialportion 50 a having a plurality of ducts. Axial portion 50 a issuspended by a suspension arm 50 b ascending and descending ascontrolled by an ascending and descending mechanism (not shown). Morespecifically, as suspension arm 50 b ascends and descends, lid 50 isvertically moved relative to an upper portion of processing cup 55 andthus operated to open and close as a lid. Note that lid 50 has a lowerperimeter provided with an O ring or a similar sealing member 50 c sothat when lid 50 contacts (or engages with) processing cup 55 aninternal processing space is sealed.

Furthermore, axial portion 50 a has a first solvent feeding path 50 dconnected to a solvent feeding mechanism 57 feeding a solvent, and aresist liquid feeding path 50 e connected to a resist feeding mechanism59 feeding resist liquid. The first solvent feeding path 50 d has an endprovided with a nozzle 12 for dropping the solvent onto wafer W andresist liquid feeding path 50 e has an end provided with a nozzle 13 fordropping the resist liquid onto wafer W. Note that resist feedingmechanism 59, resist liquid feeding path 50 e and nozzle 13 togetherconfigure a device feeding liquid to be applied.

Furthermore, axial portion 50 a also has a second solvent feeding path50 f and a dry air feeding path 50 g connected to a circulation path 14and a dry air feeding duct 25, respectively.

In this example, circulation duct 14 is connected to the second solventfeeding path 50 f and exhaust port 55 c with a gas-liquid separator 14a, an air blowing fan 14 b, a filter 14 c and a valve 14 d interposedtherebetween.

Furthermore circulation duct 14 between air blowing fan 14 b and filter14 c is connected to a discharging pipe 14 f connecting to a tank 14 eaccommodating a solvent such as thinner B for the resist liquid.Furthermore, tank 14 e is connected to a source of carrier gas (notshown) via a carrier gas feeding pipe 14 g.

Thus an atmosphere control device is configured. The source of carriergas feeds thinner B in tank 14 e with a carrier gas, such as He gas,which allows thinner B to flow into circulation duct 14. In circulationduct 14 air flows, which allows thinner B to form a mist and be fed toprocessing space 15.

Dry-air feeding duct 25 is connected to a dry-air feeding path 50 g anda dehumidifier 25 e with a valve 25 a, a filter 25 b, an air blowing fan25 c and a temperature controller 25 d interposed therebetween.

In this configuration dehumidifier 25 e dehumidifies air to have apredetermined humidity for example of 40% or lower and temperaturecontroller 25 d controls the dehumidified air to have a predeterminedtemperature, e.g., room temperature (approximately 23° C.). The air thusdehumidified and controlled in temperature is fed to processing space15.

Resist application process unit 20 configured as described aboveperforms a resist application process, as described hereinafter.

Initially, lid 50 is moved upward, while wafer W is loaded, andsubstantially horizontally chucked on spin chuck 51 moved upward byascending and descending mechanism 53.

Wafer W chucked on spin chuck 51 is moved by ascending and descendingmechanism 53 into processing cup 55 and receives on an upper surface atthe center a predetermined amount of a solvent dropped through nozzle12. Spin chuck 51 is then rotated by rotation mechanism 52 and thesolvent dropped on wafer W is dispersed on wafer W, and while thesolvent is being dispersed, the resist liquid is dropped through nozzle13.

Furthermore, simultaneously, lid 50 descends to seal processing cup 55to form processing space 15 and the thinner fed into circulation duct 14in the form of a mist is also fed through the second solvent feedingpath 50 f into processing space 15, and in that condition the resistliquid is dispersed across the surface of wafer W.

After the resist liquid is dispersed across the surface of wafer W,valve 14 d is closed and simultaneously valve 25 a is opened to feed dryair into processing space 15 to clear processing space 15 of theatmosphere of the thinner. Alternatively, rather than feeding processingspace 15 with dry air, lid 50 may be moved upward to clear processingspace 15 of the atmosphere of the thinner. At the same time as theatmosphere is cleared away, wafer W is dried as it is spun to form afilm of the resist.

Note that in the resist liquid dispersion process wafer W scattersaround an excessive amount of the resist liquid, which is recovered byprocessing cup 55 and partially forms a mist in processing cup 55.

In processing cup 55, as an aspiration device (not shown) is driven, anexhaust flow path is formed to extend from aspiration port 55 a toexhaust port 55 c. The mist formed in processing cup 55 passes throughthe exhaust flow path as an unnecessary atmosphere together withexternal air aspirated through aspiration port 55 a and is thusexhausted through exhaust port 55 c.

Thus the present invention in the second embodiment allows resist liquidto be dispersed on a surface of wafer W in a sealed processing spacewith a processing atmosphere fed with a solvent (a thinner) for theresist liquid in the form of a mist to suppress evaporation of thesolvent dispersed and thus prevent a substrate from having a perimeterwith the dispersed resist liquid dried and thus solidified thereon.

Thus in addition to the effect obtained in the first embodiment theresist liquid can form a film more uniform in thickness, and the resistliquid can also be reduced in amount for use and exhaust and effluentcan also be reduced in amount.

Note that, as has been described in the first and second embodiments,aspiration port 55 a is provided with flowmeter 46. If an aspirationdevice performing aspiration through exhaust port 55 c is not driven andthus stops, however, there is a possibility that processing cup 55 mayhave the mist remaining therein and thus flowing back into aspirationport 55 a and contaminating flowmeter 46.

Accordingly, as shown in FIG. 6 showing an enlarged view of a vicinityof aspiration port 55 a, a back flow preventing portion 33 is preferablyprovided that is formed of a plurality of air stream controlling plates33 a positioned in the exhaust flow path downstream of flowmeter 46 andinclined such that it does not affect aspirating external air andsuppresses the mist that flows backward. Backflow preventing portion 33further ensures that flowmeter 46 is protected against contamination.

Furthermore while the aforementioned embodiments have been describedsuch that a substrate to be processed is a semiconductor wafer by way ofexample, the present invention may be applied to a substrate other thana semiconductor wafer and is applicable to a LCD substrate, a CDsubstrate, a glass substrate, a photomask, a printed circuit board andthe like.

The present invention is applicable for example to a resist applicationprocess unit processing a semiconductor wafer or a similar substrate andcan suitably be employed in the industries of semiconductor production,electronic device fabrication and the like.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the spiritand scope of the present invention being limited only by the terms ofthe appended claims.

1. A method of forming an applied film, dropping on a substrate a liquidto be applied thereon, and rotating said substrate to cause a force todisperse said liquid in a form of a film to form a film applied on anupper surface of said substrate, comprising the steps of: holding saidsubstrate substantially horizontally on a substrate holding and rotatingdevice; dropping said liquid on an upper surface of said substraterotating on said substrate holding and rotating device; and exhaustingan unnecessary atmosphere produced in forming said film applied on saidsubstrate, wherein the step of exhausting is performed such that aprocessing space located above said substrate and a space located belowsaid substrate are substantially separated.
 2. The method according toclaim 1, wherein the step of dropping said liquid is performed such thatsaid processing space located above said substrate is substantiallysealed.
 3. The method according to claim 2, wherein the step of droppingincludes the step of feeding said processing space with a solvent forsaid liquid in a form or a mist, and wherein, with said solvent fed insaid mist, said liquid is dispersed as said substrate is rotated.